Alkylation of aromatic hydrocarbons



Patented May 1-, 1945 ALKYLATION OF AROMATIC HYDROCARBONS Louis Schmerling and Vladimir N. Ipatieil, Chicago, Ill., assignors toUniversal Oil Products Company, Chicago, 111., a corporation of Dela- NoDrawing. Application August 11, 1941, Serial N0. 406,408

13 Claims. (Cl. 260- 671) This invention relates to the treatment ofarcmatic hydrocarbons to produce alkylated aromatic hydrocarbons. Morespecifically it is concerned with the production of mono-alkylated andpoly-alkylated aromatic hydrocarbons in the presence of a catalyst. Itis recognized that in generalthe catalytic alkylation of aromatichydrocarbons has been known for some time. However, the presentinvention differentiates from the prior art on this subject in the-useof a particular catalytic material comprising as its active ingredientcupric orthophosphate or a material formed by calcinoing cupricorthophosphate at a temperature of from about 200 to about 400 C.

In one specific embodiment the present invention comprises a process forproducing alkylated aromatic hydrocarbons which comprises subjecting anaromatic hydrocarbon and an olefinic hydrocarbon to contact under.alkylating conditions in the presence of a catalyst containing as itsactive ingredient a material formed by calcining cupric orthophosphate.

Aromatic hydrocarbons, such as benzene, toluene; other alkylatedbe'nzenes, naphthalene, alkylated naphthalenes, other poly-nucleararomatics, etc., which are-alkylated by oleflnic hydrocarbons ashereinafter set forth, may be obtained by the distillation of coal, bythe dehydrogenation of naphthenic hydrocarbons, by the dehydrogenationand cyclization of aliphatic hydrocarbons, alkylated aromatichydrocarbons, and alkylated naphthenic hydrocarbons,. and by othermeans.

Olefinic hydrocarbons utilizable as alkylating agents in the presentinstance comprise monoolefins and poly-olefins. Olefins which areemployed in'the present process are either normally gaseous or normallyliquid and comprise ethylene and its higher homologs, both gaseous andliquid, the latter including various polymers of normally gaseousolefins, but these different olefinic hydrocarbons and those mentionedhereinafter are not necessarily equivalent in their action as alkylatingagents. Cyclic olefins may also serve in alkylating aromatichydrocarbons but generally under conditions of operation diiiernt from'those employed when alklating aromatic hydrocarbons bynon-cyclicolefins, and this reaction may involve intermediate formation of olefinsfrom cycloparaflins in the presence of the catalyst. Other olefinichydrocarbons which may be interacted with the above indicated aromatichydrocarbons include conjugated diolefins such as butadiene andisoprene, also non-conjugated diolefins, and other poly-olefins.

Oleflnic hydrocarbons utilizable as alkylating agents are obtainablefrom any source and are present in products of thermal and catalyticcracking of oils, in those obtained by dehydrogenating paraflinic andoleflnic hydrocarbons or in the products resulting from dehydratingalcoa hols.

Alkylation of aromatic compounds may also be eiiected in the presence ofcatalysts hereinafter described by charging with the aromatichydrocarbon a substance capable of producing oleflnic hydrocarbons underthe operating conditions chosen for the reaction. Such olefin-producingsubstances include alcohols, ethers, esters, and alkyl halides which arecapable of undergoing dehydration or splitting to olefinic hydrocarbons,containing at least 2 carbon atoms per molecule, which may be consideredas present in the reaction mixture even though possibly only astransient intermediate compounds which react further with aromatichydrocarbons to produce desired reaction products.

Catalysts suitable for'use in effecting the process of the presentinvention comprise cupric orthophosphate or a material formed bycalcining hydrated cupric orthophosphate at a temperature generallywithin the range utilized in the alkylation reaction namely from about200 I to about 400 C. The hydrated cupric orthophosphate, thecorresponding anhydrous salt, or a copper phosphate with an intermediatedegree of hydration is utilizable as alkylating catalyst either as suchor composited with a carrier such as alumina, silica, silica-aluminacomposites, diatomaceous earth, crushed porcelain, pumice, firebrick,etc; The addition to the catalyst, before final drying thereof, of freephosphoric acid may increase the alkylating activity of the resultingcomposite catalyst.

A composite catalyst of the typ hereinabove described in finely powderedform is thoroughly mixed, then subjected to drying, pelleting, andheating operations, the latter carried out in a stream of air, nitrogen,or hydrocarbon gases, etc., to produce formed particles of catalystsuitable for use as packing material in a reactor employed for effectingalkylation of aromatic hydrocarbons by olefinic hydrocarbons. Also, thecopper orthophosphate or material formed by calcining this salt may besimilarly formed into partiary carbon atom as is present in isobutene,trimethyl ethylene, etc. The difierent alkylating catalysts which may bethus prepared and employed in the present process are not necessarilequivalent in their action. 7

Cupric phosphate contains no acidic hydrogen atoms but nevertheles it isan active alkylatin catalyst. Although the reactions of this metallic Yular proportion of olefinic hydrocarbon to between about 400 C. under apressure of from substantially atmospheric to approximately 100atmospheres. Intimate contact of the reacting components with thecatalyst is effected by passing the reaction mixture through a fixed bedof granular or pelleted catalyst or the reacting components may be mixedwith finely divided catalyst and reacted in either a batch or continuoustype of operation. Thehydrocarbons subjected to reaction are preferablyin the proportion of 1 molecabout 2 and about molecular proportions ofaromatic hydrocarbon in order to diminish polymerization-of olefinichydrocarbons and to favor i5 salt are not understood completely, thealkylating activity of copper orthophosphate which contains water ofcrystallization may be due to partial hydrolysis under operatingconditions to produce certain amounts of free phosphoric acid asillustrated by the following equation:

Cu: (P04) 2 ZCLKOH) 2+CuP20s-f-4H20 The products obtained by heating thetrihydrate appeared to consist chiefly of a basic metaphosphate ofcopper having the same empirical formula as that of cupricpyrophosphate. However, the latter compound as well as theorthophosphate dissolve readily in ammonium hydroxide yielding the deepblue color characteristic of cupric-ammonium compounds, while thecalcination product does not dissolve. Thus it is probable that theactive ingredient of the alkylating catalyst is not trihydrated cupricphosphate but possibly a partially dehydrated or anhy drous copperphosphate or an acid copper pyrophosphate, the latter formed byreduction of part of the catalyst composite.

In effecting reaction between aromatic hydrocarbon and an alkylatingagent, as an olefinic hydrocarbon, according to the process of thepresent invention, the exact method of procedure varies with the natureof the reacting constituents. A simple procedure, utilizable in the caseof an aromatic hydrocarbon which is normally liquid. or if solid isreadily soluble or easily dispersible in a substantially inert liquid,and a normally gaseous or liquid olefinic hydrocarbon, consists incontacting the aromatic and olefinic hydrocarbons with a catalystcontaining copper orthophosphate or a material formed by calciningcopper orthophosphate under the alkylating conditions which comprise atemperature of from about 200 to interaction of olefinic hydrocarbonswith the aromatic hydrocarbon or mixture of aromatic hydrocarbons in thehydrocarbon fraction undergoing treatment. The addition of ahydrogen-containing gas to the alkylation mixture frequently has abeneficial effect upon the reaction.

Thus a hydrocarbon mixture comprising essentially normally liquidaromatic hydrocarbons and a fraction containing olefinic hydrocarbonsare commingled and passed through a reactor containing a catalyst asherein described, or at least a portion of the aromatic hydrocarbon ischarged to such a reactor while the fraction containing olefinichydrocarbons, as such or preferably diluted by another portion of thearomatic hydrocarbon being treated, is introduced at various pointsbetween the inlet and the outlet of the reaction zone in such a way thatthe reaction mixture being contacted with the catalyst will at all timescontain a relatively low proportion of the olefinic hydrocarbon and thusfavor interaction of aromatic and olefinic hydrocarbons rather thanpolymerization of the latter.

While the method 01' passing the aromatic and olefinic hydrocarbons,either together or countercurrently, through a suitable reactorcontaining the granular catalyst is generally customary procedure, theinteraction of these hydrocarbons may also be eflected in a closedvessel in which some of the reacting constituents are in liquid phaseand in which the catalyst is preferably in finely divided form and ismaintained in dispersion or suspension by some method of agitation. Thechoice of operating procedure is dependent upon the circumstances suchas the temperature, pressure, and activity of catalyst found to be mosteffective for producing the desired reaction between particular aromaticand olefinic hydrocarbons.

Copper phosphate-containing catalysts as herein described are preferredbecause they permit continuous reaction of aromatic and olefinichydrocarbons in the presence of a fixed bed of catalyst and thus make itpossible to avoid mechanical problems as well as oxidation and corrosiondifficulties encountered when this reaction is carried out in thepresence of sulfuric acidwhich is sometimes used as an alkylatingcatalyst. Further, a catalyst of the described type also has theadvantage over aluminum chloride utilized as catalyst for alkylatingaromatic compounds with olefinichydrocarbons in that the copperphosphatecontaining catalyst forms substantially no addition compoundsor complexes with aromatic and/or olefinic hydrocarbons as ischaracteristic of catalysts containing aluminum chloride.

Reactions between aromatic and olefinic hydrocarbons in the presence ofthe herein described catalysts are apparently of a relatively simplecharacter, although they may be'accompanied by certain amounts ofpolymerization and decommeans.

position. While not understood completely, a typical alkylation of anaromatic hydrocarbon by an olefin apparently involves the addition ofthe aromatic hydrocarbon to a double bond of an olefinic hydrocarbon toproduce a higherboiiing alkylated aromatic hydrocarbon which may in turnundergo further reaction-with one or more molecular proportions ofolefinic'hydrocarbons to form dialkylated and more-highly alkylatedaromatic hydrocarbons. In case the alkylating olefinic hydrocarbon isadiolefin or other poly-olefin containing'more than one double bond permolecule, the interaction with an aromatic hydrocarbon may involve notonly the combination of aromatic and olefinic hydrocarbons but possiblythe polymerization of a higher boiling unsaturated aromatic hydrocarbonresulting from the primary reaction. Thus benzene and 1,3-butadienegive, among other products, a substantial yield of phenyl butene whichpolymerizes to form dimers of phenyl butene. Within certain limits it ispossible to produce mainly mono-alkylated aromatic hydrocarbons byproper adjustment of catalyst activity, ratio of the aromatic to theolefinic hydrocarbons charged, operating conditions such as temperature,pressure, and rate of feed of the reacting components, etc.

The reaction between an aromatic hydrocarbon and a hexene or othernormally liquid olefln of higher molecular weight may involve not onlyaddition of aromatic and oleilnic hydrocarbons but also adepolymerization or splitting of the olefinic hydrocarbon into olefinicfragments of lower molecular weights which react with the aromatichydrocarbons to produce alirylated aromatic hydrqcarbons. Thus benzeneand di-isobutene or tri-isobutene react and yield tertiary butylbencate'd ranges because of the fact that cupric phospate undergoeshydrogenation to form free copper and phosphoric acid. Thus when partsby weight of cupric orthophosphate trihydrate was which correspondedquite closely-to the theoretical yield of 22.6 parts byweight.

The following examples are given to illustrate the character of resultsobtainable by the use of the present process, although the examplesgiven are not introduced with the intention of unduly restricting thegenerally broad scope of the invention.

Example I In a batch type operation 80 parts by weight of benzene, 20parts by weight of propene, and 10 parts by weight of cupric phosphatetrihydrate were placed in an autoclave, nitrogen was added thereto to 50atmosphere initialpressure and the reaction mixture was heated 4 hoursat 300 C. 90 parts by weight of liquid products were thus obtained whichcontained 32 parts by weight of mono-isopropyl benzene, and 7 parts byweight of a mixture of di-isopropyl benzene and morezeneandpoly-tertiary butyl benzenes, while nonene and benzene yield both butyland amyl benzenes as well as other products by so-calleddepoly-alkylation.

In general, the products formed by interaction of an olefinichydrocarbon with a molal excess of an aromatic hydrocarbon are separatedfrom the unreacted aromatic hydrocarbon by suitable means as bydistillation, and the unreacted portion of the aromatic hydrocarbonoriginally charged and generally the poly-alkylated hydrocarbons formedare returned to the process and mixed with'additional quantities of theolefinic and aromatic hydrocarbons being charged to contact with thecatalyst. This recycling of polyalkylated aromatichydrocarbons'sometimes aids inthe production of mainly mono-alkylatedaromatic hydrocarbons and depresses the formation of more-highlyalkylated derivatives. The total alkylated product thus freed from theexcess of the originally charged aromatic hydrocarbon is separated intodesiredfractions by distillation at ordinary or reduced pressure or byother suitable While the process'of this invention'is particularlyapplicable to the production of alkylated aromatic hydrocarbons fromaromatic and olefinic hydrocarbons, it may be utilized also inalkylating other aromatic compounds as in converting phenols andolefinic hydrocarbons into alkylated phenols using a catalyst containingcopper orthophosphate or a material formed by calcining copperorthophosphate and generally operating within the range of temperatureand pressure hereinabove set forth.

The presence in the reaction mixture of large amounts of hydrogen isgenerally not desirable highly propylated benzenes. Upon the basis ofthe propene charged, the yield of mono isopropyl benzene wa 56% of thetheoretical.

Example II 50 parts by weight of cupric orthophosphate trihydrate washeated in an autoclave for 4 hours at 300 C. under 50'atmospheresinitial nitrogen pressure and thereby converted into 43.5 parts byweight of bluish green powder.. This weight change corresponded toa'loss of 3 molecules of water per molecule .of copper phosphatetrihydrate so treated. The bluish green powder so formed by heating thehydrated cupric phosphate was probably a basic phosphate and not justcupric pyrophosphate since the powder obtained reacted only very slowlywith ammonium hydroxide while cupric pyrophosphate dissolves immediatelyin ammonia yielding the familiar type of blue solution containingcopper-ammonium compounds.

Propylation ofbenzene parts by weight) by propene (20 parts by weight)in the presence of 10 parts by weight of the described bluish greenpowder was made by heating this mixture at 350 C. for 4 hours in thepresence of nitrogen under an initial pressure of 50 atmospheres. Thereaction mixture so formed contained 39 parts by weight ofmono-isopropyl benzene and 10 parts by weight of more-highly propylatedbenzenes.

Another run made under the-same conditions but in the presence of 5parts by weight of the calcined cupric phosphate and 4 parts by weightof'water yielded 38 parts by weight of mono isopropyl benzene and '7parts by weight of morehighly proplyated benzenes.

reactor through which benzene and ethylene were particularly whenoperating under a relatively high temperature and pressure within theindipassed continuously. In each or three runs 70 parts by weight ofbenzene (80 volumes) and 14 parts by weight of ethylene were passed perhour through 40 volumes of catalyst under a pressure of 600 pounds persquare inch and at the temperatures shown in the following table:

Table-Ethylation of benzene Ethyl benzenes, parts by Time, hoursCatalyst weight per hour Run N 0. since begintempers ning of run ture, CMono- Di- Residue Run #1 showed that little if any alkylation occurredat a temperature below 350 C. and that substantially complete absorptionof the ethylene did not occur until the temperature was about 400 C. Inrun #2 17 hours at about 385 C. the catalyst decreased in activity asthe run prograssed and the yield of ethyl benzene dropped about 35%. Run#3 showed that it wasbeneficial to initially use a relatively highcatalyst temperature and to decrease this temperature as the runprogressed. In this run in which the catalyst temperature was kept atabout 385 C. during the first 3 hours, then'lowered to about 320 C.during the next 5 hours and kept at that temperature for 9 hours, thecatalyst showed an activity at 320 C. equal to that obtained at 385 C.with fresh-catalyst. There was no drop in activity during a period of 9hours at about 320 C., and when the catalyst temperature was thenlowered to 262 C. a substantial yield of ethyl benzene was stillobtained which was higher than that obtained at 363 C. in run #1.

From the results of these runs it appears that 'thecatalyst formed fromcopper phosphate requires a preliminary activation which is accomplishedby use of a high initial temperature followed by a period of processingat a lower temperature at which there is less formation of carbon uponthe catalyst than when a higher catalyst temperature is necessary duringthe entire run.

The character of the invention andthe type of results obtainable by itsuse in practice will be evident from the preceding specification andexample given, although they are not to be considered as imposing unduelimitations upon its generally broad scope.

We claim as our invention:

1. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aro-' matic hydrocarbon and an oleflnichydrocarbon to contact under alkylating conditions in the presence of acatalyst containing as its active ingredient a material formed bycalcining cupric orthophosphate.

2. A process for producingv alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and an oleflnic hydrocarbonto contactat a temperature of from about-200 to about 400 C. under apressure 01' from substantially atmospheric to approximately 100atmospheres in the presence of a catalyst containing as its activeingredient a material formed by calcining cupric orthophosphate.

4. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting from about 2 to about 20 molecular proportions ofan aromatic hydrocarbon and 1 molecular proportion of an oleflnichydrocarbon to contact at a temperature or from about 200 to about 400C. under a pressure oi. from substantially atmospheric to approximately100 atmospheres in the presence of a catalyst containing as its activeingredient a material formed by calcining cupric orthophosphate.

5. A process for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and a normally gaseousolefinic hydrocarbon to contact at a temperature of from about 200 toabout 400 C. under a pressure of from substantially atmospheric toapproximately 100 atmospheres in the presence of a catalyst containingas'its active ingredient a material formed by calcining cupricorthophosphate.

' 6. A iprocess for producing alkylated aromatic hydrocarbons whichcomprises subjecting an aromatic hydrocarbon and a normally liquidolefinic hydrocarbon to contact at a temperature of from about 200 toabout 400 C. under a pressure of from substantially atmospheric toapproximately 100 atmospheres in the presence of a catalyst containingas its active ingredient a material formed by calcining cupricorthophos- 7: phate.

7. A process for producing alkylated benzenes which comprises subjectingfrom about 2 to about 20 molecular proportions oi benzene and 1molecular proportion 01' an olefinic hydrocarbon to contact at a.temperature of from about 200 to about 400 C. under a pressure of fromsubstantially atmospheric to approximately 100 atmospheres in thepresence of a catalyst containing as its active ingredient a materialformed by calcining cupric orthophosphate.

8. A process for producing alkylated benzenes which comprises subjectingfrom about 2 to about 20 molecular proportions of benzene and 1molecular proportion 01' a normally gaseous oleflnic hydrocarbon tocontact at a temperature of from about 200 to about 400 C. under apressure of from substantially atmospheric to approximately 100atmospheres in the presence of a catalyst containing as its activeingredient a ma- =terial formed by calcining cupric orthophosphate.

9. A process for producing alkylated benzenes which comprises subjectingfrom about 2 to about 20 molecular proportions of benzene and lmolecular proportion of a. normally liquid olefinic hydrocarbon tocontact at a temperature of from about 200 to about 400 C. under apressure 01' from substantially atmospheric to approximately atmospheresin the presence of a catalyst containing as its active ingredient amaterial formed by calcining cupric orthophosphate.

10. A process for producing propylated benzenes which comprisessubjecting from about! to about 20 molecular proportions of benzene andl-molecular proportion of prop'ene tocontact at a temperature of fromabout 200 to about 400 C. under a pressure of from substantiallyatmospheric to approximately 100 atmospheres in the presence of acatalyst containing as its active ingredient a material formed bycalcining cupric orthophosphate. 11. A process for producing ethylatedbenzenes which comprises subjecting from about 2 to about 20 molecularproportions of benzene and 1 molecular proportion of ethylene to contactat a. temperature of from about 200 to about 400 C;

under a pressure" of from substantially atmospheric to approximately 100atmospheres in the presence of a catalyst containing as its activeingredient a material formed by calcinins hydrated cupricorthophosphate. r

' 12. An alkylation process which comprises reacting an aromatichydrocarbon with an olefin in the presence of cupric orthophosphate.

- 13. An alkylation process which comprises reactingan aromatichydrocarbon with an olefin in the presence of a catalyst resulting fromthe calcinati'on of hydrated cupric orthophosphate.

LOUIS vmnmm min-1mm.

